1. Field of the Invention
The present invention relates to an aerosol generating apparatus, a method for generating aerosol and a film forming apparatus.
2. Description of the Related Art
As example of a method for producing a piezoelectric actuator used, for example, for an ink-jet head of an ink-jet printer, there is aerosol deposition method (AD method). In the AD method, aerosol formed by dispersing fine particles of a piezoelectric material such as lead zirconate titanate (PZT) or the like in a gas (aerosol) is ejected (jetted) toward a surface of a substrate to make the fine particles collide on and to be deposited onto the substrate, thereby forming a piezoelectric film.
In the AD method, as an example of a mechanism for generating the aerosol, there is known a mechanism for generating aerosol provided with a vibrating unit (see Japanese Patent Application Laid-open No. 2001-152360). This aerosol generating mechanism includes a gas cylinder, an aerosol generating chamber, and a vibrating unit, and introduces a carrier gas from the gas cylinder to the aerosol generating chamber so as to raise particulate material (material particles) up with gas pressure of the carrier gas and to vibrate a container of the aerosol generating chamber to which the carrier gas and the particulate material are introduced, thereby mixing the particulate material and the carrier gas to generate aerosol. The generated aerosol is sucked to a delivery tube by a pressure difference between the aerosol generating chamber and a film forming chamber so that the aerosol is introduced to a nozzle in the film forming chamber. Then, the aerosol is ejected from this nozzle toward a substrate.
Other than this mechanism, there has been also proposed a mechanism adopting suction system in which particulate material is sucked together with a carrier gas by suction force generated when the carrier gas is sucked into a delivery tube.
In order to perform film formation stably, it is important to maintain a concentration of aerosol generated in the aerosol generating chamber (aerosol concentration) to be constant. In the above-described mechanism provided with the vibration unit, however, there is a problem that the particulate material is gradually aggregated and solidified due to the applied vibration, and consequently the particulate material loses fluidity, thereby lowering the aerosol concentration. On the other hand, with the apparatus adopting the suction system, there is a problem that the particulate material easily clogs at an inlet of the delivery tube.